Thursday, July 30, 2009



WATER PURIFICATION AND SIMPLE TECHNOLOGY
Access to clean drinking water is taken for granted in most countries across the world. However, in many third world countries clean drinking water is not always available. Many people, especially children, suffer from diseases contracted from drinking water infected with salmonella, E-coli bacteria and many other forms of bacteria. Drinking impure water can be fatal and at best cause severe diarrhoea. Diarrhoea dehydrates the body and often the sufferer drinks more contaminated water in an attempt to replace the water his/her body has lost.A basic water filter can purify ‘dirty’ water making much safer to drink. The filter is based on simple technology and one example is shown below. It is composed of quite common materials and is relatively easy to put together. Technology does not always need to be complex or computer controlled to be effective and useful.
The ‘dirty’ water is poured into the top of a tank which contains layers of sand, charcoal and gravel. As the water sinks through the various layers the bacteria and dirt are removed. The clean water flows through a hose/pipe into a ‘clean’ water storage tank. The water is now safe to drink. This is simple technology helping people live safer and longer lives.

Wednesday, July 29, 2009





Have a look at the photograph on the right. Can you imagine how long it would take a skilled worker to ‘carve’ this shape out of wood or a soft material - it would probably take a full day. We will be going through its manufacture, one step at a time using a CNC machine (next page). How long do you think manufacturing this product with a CNC machine will take ?


THE CNC MACHINE


The VICE: This holds the material to be cut or shaped. Material must be held securely otherwise it may 'fly' out of the vice when the CNC begins to machine. Normally the vice will be like a clamp that holds the material in the correct position.


The GUARD: The guard protects the person using the CNC. When the CNC is machining the material small pieces can be 'shoot' off the material at high speed. This could be dangerous if a piece hit the person operating the machine. The guard completely encloses the the dangerous areas of the CNC.

The CHUCK: This holds the material that is to be shaped. The material must be placed in it very carefully so that when the CNC is working the material is not thrown out at high speed.

The MOTOR: The motor is enclosed inside the machine. This is the part that rotates the chuck at high speed.

The LATHE BED: The base of the machine. Usually a CNC is bolted down so that it cannot move through the vibration of the machine when it is working.

The CUTTING TOOL: This is usually made from high quality steel and it is the part that actually cuts the material to be shaped.

1. Draw a small CNC machine and label the most important parts.
2. List the safety factors that people must be aware of before they operate a CNC or similar machine

Thursday, July 23, 2009

ALTERNATIVE ENERGY SOURCES




SOLAR ENERGY
Solar power is energy from the sun and without its presence all life on earth would end. Solar energy has been looked upon as a serious source of energy for many years because of the vast amounts of energy that are made freely available, if harnessed by modern technology.A simple example of the power of the sun can be seen by using a magnifying glass to focus the suns rays on a piece of paper. Before long the paper ignites into flames.
This is one way of using the suns energy, but flames are dangerous and difficult to control. A much safer and practical way of harnessing the suns energy is to use the suns power to heat up water.
A magnifying glass can be used to heat up a small amount of water। A short piece of copper tube is sealed at one end and filled with water. A magnifying glass is then used to warm up the pipe. Using more than one magnifying glass will increase the temperature more rapidly. After a relatively short time the temperature of the water increases. Continuing to heat the water will cause water vapour to appear at the top of the tube. In theory, with enough patience, several magnifying glasses and very strong sun light enough heat should be generated to boil the water, producing steam. This is one way of harnessing solar power.



AIR MOVES FORMING WINDS
Wind power is generated by moving air. As the sun heats the land, the air above also warms and rises. Cold air then replaces the rising air. This creates the winds that we feel most days of the year. The diagram below shows how this ‘system’ works.Air tends to warm at a faster rate over land because the land retains its heat. Over the sea the air warms more slowly as heat by the sun is slowly cooled by the cold water. If you visit the seaside or coastal area you will probably find that the weather is more breezy or windy than inland. This is because the warm air rises over the land and cold air over the sea replaces it.

Throughout history people have taken advantage of the power of wind। Sail vessels have been used to travel along and across rivers, seas and lakes. For example, the Vikings used long ships with sail from Europe to England, Scotland, Wales and Ireland. It is also believed that they travelled even as far as North America, all through the use of wind power.It is also known that the Chinese over 1500 years ago had large sailing vessels and travelled as far as Africa.It is difficult to think of a time when people have not made great use of the power of the wind.



SEA POWER
The power of the tide can be seen in this photograph. It shows people running for their lives from a powerful tidal wave which has crashed over a coastal/river wall (China 2000). If tidal power can be harnessed electricity can be produced in large quantities.

The Earth is covered mainly by water। The seas as we call them, have currents and tides that circulate round the world. This vast amount of moving water produces immense amounts of energy. Countries like Britain that are surrounded by powerful seas and oceans are ideally placed to convert the energy of tides, sea currents and waves to produce electrical energy. The main problem in harnessing sea power is that it is not easy and usually means investment of large amounts of money. Also, quite advanced engineering and technology are required to convert sea power to electrical power.The power of the sea can be harnessed in three main ways; through the energy of waves, the energy of sea currents and tides.

DAMS / HYDRO ELECTRICITY
Water has been used to power industry for hundreds years. The example below shows a water wheel being driven round by a river / stream. As the water wheel turns, a shaft running through its centre would be used to power machines through a range of pulleys. This was the main form of power during the early years of the Industrial Revolution.
Water wheels were the fore-runner of our modern day water driven electrical turbines.
To increase the power provided by water a dam is added। This is seen in the diagram below. The dam allows a ‘head’ of water to build up. The water can be release when power is needed to drive machines inside the building/factory. This system provides more power because:1. A powerful ‘head’ of water is built up behind the dam.2. When the water is released, it is directed to the top of the water wheel. The wheel spins faster because gravity aids the falling water, pushing the wheel round at a higher speed.




NUCLEAR POWER GENERATION
Nuclear Power Stations use a fuel called uranium, a relatively common material. Energy is released from uranium when an atom is split by a neutron. The uranium atom is split into two and as this happens energy is released in the form of radiation and heat. This nuclear reaction is called the fission process
In a nuclear power station the uranium is first formed into pellets and then into long rods. The uranium rods are kept cool by submerging them in water. When they are removed from the water a nuclear reaction takes place causing heat. The amount of heat required is controlled by raising and lowering the rods. If more heat is required the rods are raised further out of the water and if less is needed they lower further into it.
GENERAL ADVANTAGES AND DISADVANTAGES OFNUCLEAR POWER GENERATION



DISADVANTAGES:1. Nuclear power is a controversial method of producing electricity. Many people and environmental organisations are very concerned about the radioactive fuel it needs. 2. There have been serious accidents with a small number of nuclear power stations. The accident at Chernobyl (Ukraine) in 1986, led to 30 people being killed and over 100,000 people being evacuated. In the preceding years another 200,00 people were resettled away from the radioactive area. Radiation was even detected over a thousand miles away in the UK as a result of the Chernobyl accident. It has been suggested that over time 2500 people died as a result of the accident. 3. There are serious questions to be answered regarding the storage of radioactive waste produced through the use of nuclear power. Some of the waste remains radioactive (dangerous) for thousands of years and is currently stored in places such as deep caves and mines.4. Storing and monitoring the radioactive waste material for thousands of years has a high cost.5. Nuclear powered ships and submarines pose a danger to marine life and the environment. Old vessels can leak radiation if they are not maintained properly or if they are dismantled carelessly at the end of their working lives.6. Many people living near to nuclear power stations or waste storage depots are concerned about nuclear accidents and radioactive leaks. Some fear that living in these areas can damage their health, especially the health of young children.7. Many Governments fear that unstable countries that develop nuclear power may also develop nuclear weapons and even use them.ADVANTAGES:1. The amount of electricity produced in a nuclear power station is equivalent to that produced by a fossil fuelled power station.2. Nuclear power stations do not burn fossil fuels to produce electricity and consequently they do not produce damaging, polluting gases. 3. Many supporters of nuclear power production say that this type of power is environmentally friendly and clean. In a world that faces global warming they suggest that increasing the use of nuclear power is the only way of protecting the environment and preventing catastrophic climate change. 4. Many developed countries such as the USA and the UK no longer want to rely on oil and gas imported from the Middle East, a politically unstable part of the world.5. Countries such as France produce approximately 90 percent of their electricity from nuclear power and lead the world in nuclear power generating technology - proving that nuclear power is an economic alternative to fossil fuel power stations. 6. Nuclear reactors can be manufactured small enough to power ships and submarines. If this was extended beyond military vessels, the number of oil burning vessels would be reduced and consequently pollution.

DIGITAL ELECTRONICS - LOGIC CIRCUITS

Most modern electronic devices such as mobile telephones and computers depend on digital electronics. In fact, most electronics about the home and in industry depend on digital electronics to work.Digital electronics normally based on ‘logic circuits’. These circuits depend on pulses of electricity to make the circuit work. For instance, if current is present - this is represented as ‘1’. If current is not present, this is represented as ‘0’. Digital electronics is based on a series of 1s and 0s.


A good example of a digital electronic system is a mobile phone. As you speak into the phone, the digital electronic circuits it contains converts your voice into a series of electronic pulses (or 1s and 0s). These are transmitted and the receiving mobile phone then converts the digital pulses back into your voice. Digital circuits are used because they are efficient and work well, also, digital signals are easier to transmit than actual sound (for example a persons voice).


The various parts of a computer communicate through the use of electronic pulses (1s and 0s). Consequently digital logic circuits are ideal for the internal electronics. The main part of the computer is the motherboard. This is a complex piece of electronics that processes all the important data. For instance, when word processing, it is very important to display letters and words on the monitor. The motherboard generates the individual letters on the monitor by sending a series of 1s and 0s to the screen.
(For more information regarding digital signals see computer control)
When the computer operator presses the letter ‘H’ on the keyboard, the motherboard converts this into a digital signal composed of 1s and 0s. The ‘H’ in the form of 1s and 0s is displayed on the monitor.When you word-process a paragraph of writing all the letters/words are displayed on the monitor in a similar way. In reality the letters are not composed of 1s and 0s but as black or white pixels

MODULAR ELECTRONICS

When building a circuit it is a good idea to treat it as being made up of modules or parts. For example you may want a circuit to be composed of a switch and a bulb. To make it easier to design the circuit it is better if it is treated as two separate parts, a switch circuit and a bulb circuit. These are then joined together - to produce one completed circuit.
Circuits are often built as modules with each doing a specific job. For example, a sensor module, a transistor module, a buzzer module etc...... When these are connected together they become a single integrated circuit.




Two simple modules are seen opposite and they are clearly labelled. They can be rearranged to produce a complete circuit. When the switch is pressed the bulb lights (see below).Each module has a top rail which is positive and a lower rail which is 0 volts or negative.


The modules are linked together by electrical wires and they fit into the positive or negative connections on the electronic boards/modules. Different makes of electronic kits are available and each allows pupils to build up circuits, test them or experiment and finally to dismantle the modules so that another pupil can use them in the future.In this way circuits can be built without the need to solder and without wasting time linking each individual component using traditional methods.
Below is a temperature sensor circuit. When the temperature falls the resistance of the thermistor falls and a bulb lights. Notice how the modules are put together to form the completed circuit.


The temperature sensor is connected to a transistor which is then connected to a bulb. The transistor allows sharp switching of the bulb so that when the temperature falls the bulb comes on immediately and when it rises it goes off just as quickly. Can you draw the circuit as a circuit diagram ?

QUESTIONS
Below are some modules that can be put together to form completed circuits. Cut them out with a scissors and join them to complete the circuit questions on Sheet 3. If you require any modules that are not on this sheet, design them yourself and add them to the ones below.


1. This question refers to the example ‘temperature sensor circuit’ near the top of this section. A. Redesign the transistor module and bulb module so that they form one module.B. Draw the completed temperature sensor and transistor/bulb modules connected together. Explain how the completed circuit works.C. Draw a new temperature module, this time one that ‘triggers’ the transistor module when the temperature rises.2. A. It is found that the bulb in the completed temperature circuit does not light because the output of the single transistor is too weak. Design a new module that will provide a stronger output. B. What is this new module called ?C. Explain how this circuit works.3. Design a ‘potential divider’ module. The module is for a nine volt supply and should allow six volts to be drawn from it.4. Design a simple game or toy for a very young child. It can involve sound, lights, a motor etc... Produce a simple, clear diagram and an explanation.5. Design the circuit(s) for the toy using modules and then draw the completed circuit as a ‘circuit diagram’.You may need to design your own individual modules. Look at the photocopied sheets that have been given out in previous weeks. (Suggestion - show your knowledge by using relays, LEDs, motors etc... alter sensors so that they can be incorporated). Note, it is possible to set up components in ‘parallel’ so that they work together. (example seen below).




Remember to show your understanding of components such as relays and circuits that include ‘Darlington Pairs’ etc.... The examiner cannot give you marks for your understanding of electronics if you do not show it on paper.

Drawing Techniques

COLOURING TECHNIQUESPENCILS2H pencils - Use ordinary pencils to draw and sketch.Colouring pencils - Use pencils to colour drawings and to draw the outline of designs.CARDOverlays/backing - Use card on top of card, you could glue together two different pieces of card and then place a design brief or something similar on the top. The card will be a backing.Colour placed on card - Try shading card with a coloured pencil, use a dark colour of card and shade it with a light shade of pencil. Use the result to back text/writing.Composite drawings - See the examples in class. Drawings constructed from different colours of card can be quite striking.FELT PENS
Brush and fine line pens - see craft knife project Brush and fine line pens - See pen project.SHADINGLine shading - see cylinder examples.
Line Shading - see flat surface examplesFull shading - shade from dark to light, see examplesBLACK PEN - Use a fine black pen to draw designs.PAINTTry colour wash with water based paint.Use an airbrush to spray paint on to the paper.TRANSPARENCIESUse OHP transparencies to build up a drawing.INFORMATION TECHNOLOGYUse a range of I.T. skills including; word processing and graphics software throughout your project.

DRAWING TECHNIQUESSketch with pencils.Sketch with pens (black ink).Use pictograms and graphs.2D Drawings - front or side views.3D Drawings - Isometric - Oblique- Single point perspective and Estimated Perspective - Two point perspectiveExploded Drawings -
1. Exploded Views - 1
2. Exploded Views - 2
3. Exploded Views - 3
4. Exploded Views - 4
draw designs that are ‘in bits’, or ‘taken apart’ so that all the parts of the design can be seen easily.Sectioned views - Draw a sectional view of an idea or solution.Working Drawing - draw the front. side and plan elevations of the final solution.Use a range of lettering stylesAlways add plenty of notes to all your drawings / pictures, including collected research.Dynamic presentations - produce drawings that have parts that move e.g. ‘pop-up card’ designs or parts that rotate.Modelling - produce models of selected designs.Produce a final model of your chosen solution. This must look realistic and be well made.
Sample Models
Card Based Models
Architectural Models
Computer Generated Models
Computer Generated Systems Model (Spreadsheets)
HAVE YOU INCLUDED COMPUTER AIDED DESIGN ?